Polyurethanes and polyurethane-ureas are being applied in various fields, and are frequently used in applications such as elastic fibers among these. In particular, fibers having a polyurethane-urea structure have the property of being excellent in terms of elastic properties and extension recovery since a polyether polyol and a polyamine compound having high cohesive force were used as a soft-segment ingredient and a hard segment, respectively.
However, these polyurethane-based elastic fibers such as polyurethane and polyurethane-urea fibers have poor unwinding processability during spinning because the fibers have high stickiness to one another. Furthermore, since these elastic fibers have high frictional resistance, the fibers are apt to pose a problem, for example, that fiber breakage occurs at machines and devices disposed in processing steps, such as a spinning machine, warping machine, knitting machine, and guide.
Means for overcoming such problems by reducing frictional resistance between each machine or device disposed in processing steps and the fibers have been investigated. Examples thereof include a method in which a solid metal soap, an oil-soluble polymer, a higher fatty acid, an amino-modified silicone, or the like is added as a finishing oil to polyurethane-based elastic fibers, a method in which talc, silica, colloidal alumina, titanium oxide, or the like is dispersed as a smoothing agent in polyurethane-based elastic fibers, and a method in which a silicone diol or a silicone diamine is introduced into part of the main chain of a polyurethane (for example, patent document 1).
However, even when these methods are used, there have been problems, for example, that a sufficient sticking-preventive effect is not obtained and that the smoothing agent causes serious wear to the spinning machine, warping machine, knitting machine, guide, etc.
Furthermore, there is a problem that an oligomer which was contained in the fibers and has been extracted with the finishing oil ingredient in the warping or knitting step or solid or high-viscosity components of the finishing oil which have separated out as a solid or paste adhere in a large amount to the fibers, spinning machine, warping machine, knitting machine, guide, etc., thereby causing product staining and clogging of machines and tools. This problem has not been solved.
There hence has been a need for a process for producing a polyurethane having reduced tackiness and showing high unwinding processability, i.e., a polyurethane having high peeling property, without using the finishing oil or the smoothing agent.
Meanwhile, many reports have hitherto been made on use of a polysiloxane polyol as a raw material for a polyurethane. Examples thereof include a thermoplastic polyurethane having a high modulus of impact resilience and produced using a modified polysiloxane diol (patent document 2). Examples thereof further include elastic polyurethane fibers which give a soft and satisfactory sense of wear and which were produced using an ether-modified silicone (patent document 3).
However, the thermoplastic polyurethane described in patent document 2 has had a problem that this polyurethane is insufficient in flexibility because the modified polysiloxane diol was used in an exceedingly large amount with respect to the amount of the other polyols.
The process described in patent document 3 has had a problem that since a polyurethane is produced and an ether-modified silicone is thereafter added to the polyurethane obtained, the ether-modified silicone is apt to separate from the surface of the fibers. In addition, there has been a problem that even when it is attempted to react the ether-modified silicone during polyurethane production, the ether-modified silicone shows insufficient compatibility with other polyols and a homogeneous polyurethane is less apt to be yielded.